A biventricular pacing system includes pacing electrodes arranged at least in both the left and right ventricles of the heart. This type of systems also often includes an atrial electrode arranged in the right atrium.
The present invention is applicable both during procedures of implanting electrode leads connected to medical implants, e.g. pacemakers, defibrillators or cardioverters, and at later follow-up procedures for evaluating the positions of the electrodes in the heart. In order to achieve a desired effect of a stimulation pulse it is of great importance that the electrode surface has good contact with the heart tissue so that the tissue may be stimulated by using stimulation pulses having as low stimulation energy as possible. In biventricular systems the timing or synchronization between stimulation pulses applied to the right and left ventricle is very important in order to adapt the stimulation as much as possible to the heart's intrinsic rhythm. The synchronization is related to the cardiac output and a general object for pacemakers is to achieve as high cardiac output as possible.
In U.S. Pat. No. 6,238,420 is known a four-chamber pacing system for optimizing cardiac output and determining heart conditions. The system utilizes impedance sensing for determining optimum pacing parameters, e.g., for pacing the left ventricle so that left heart output is maximized. Impedance sensing in the left heart also provides timing of mechanical contraction, and the pacemaker controls pacing to maintain bi-ventricular mechanical synchronization adjusted for maximum cardiac output.
In connection with implantable heart stimulators it has been found very advantageous to measure the pressure in the left ventricle of the heart in order to obtain information related to the function of the heart stimulator and especially if the desired therapy is achieved by the stimulating pulses.
A pressure sensor assembly mounted on a guide wire and applicable for measuring intravascular pressure, and in particular intracardiac pressure, is disclosed in U.S. Pat. No. 5,226,423. The pressure sensor assembly is in particular applicable for insertion into the left ventricle of the heart via coronary sinus, according to well-established implantation techniques.
In the published US patent application 2002/0072880 is disclosed a system that includes an interactive graphical user interface for controlling the performance of, and for displaying on a screen, measured values and calculated results based on the measured values obtained by a guidewire-mounted pressure sensor, e.g of the kind disclosed in the above-mentioned U.S. Pat. No. 5,226,423.
The overall object with the present invention is to simplify for the physician, during the clinical procedure of implantation or follow-up, to use information obtained by pressure measurements in the left ventricle to optimize predetermined medical implant settings in a medical implant controlling the application of stimulation pulses to the left and right ventricles of the heart.